Flotation of molybdenite



April 13, 1943. c. MARSH 2,316,743

FLOTATION 0F' MOLYBDENITE 1NVENTOR Co/P//v M24/FSH,

Wm WW ATTORNEY.

2 sheets-sheet 2 C'. MARSH FLOTATION OF MOLYBDENITE Filed NOV. 9, 1939 A2Saw o a3/masa maand INVENTOR. coe//v MAPS/f ,l BY M MW AfrroRNEYf April 13, 1943.

Paienred' Apr. 13, 1943 American Cyanamid Company, New York,v

N. Y., a corporation of Maine Application November 9, 1939, Serial 'No. 303.589

claims. (ci. zoo-16s) The present invention relates to improved methods and reagents forV concentrating molybdenite by froth notation.

In the past it has been considered very dimcult to obtain molybdenite concentrates of sufficiently high grade by the use of heretofore known ilotation agents and methods. In some instances the molybdenite containing ores also contain and are closely associated with a gangue material of the mica class from which it is very diicult to selectively lloat the molybdenite. In other cases the -molybdenite may occur as relatively-large masses of impure mineral containing quartz or pyrite in which case a high recovery of the molybdenite in a high grade concentrate requires grinding Ito a f remaining suldes.

flneness far beyond the economical limits for such ores when employing previously agents. c

In many ores molybdenite is found along with other mineral sulfldes suchas copper sulfide, iron sulde. the various base metal sulfides or precious metal suiildes.

In the past two general procedures have been employed in the separation of molybdenite from the other metallic suliides. Both of these procedures have depended on a flotation of the metal in the first instance. One of the processes employs a bulk float of both molybdeniteand the other metallic suldes and the separation is then effected by av suitable treatment of the concentrate obtained. The second procedure is a differential oat, the molybdenite being depressed by the use of various reagentsfor example organic protective colloids such'as starch in an alkaline solution. In both of these procedures the rst notation step is effected in the presence of proknown flotation Y trate obtained.- In the second instance the present invention adopts exactly the opposite cour'se to that which was used in the past. Instead of carrying out a flotation procedure which results in a high recovery ofthe other metallic suldes with or without molybdenite, a differential float is employed in which a iirst concentrate is obtained which shows a high recovery of molybdenite with a relatively low recovery of the other suldes, followed if desired; by notation procedures which will result in recovering a large proportion of the The nrst notation operation is effected in the absence of ordinary sulide promoters, producing a concentrate showing good recoveries of molybdenite. The tailings can -then be treated by froth notation in the presence of promoters for th suldes.

Not all of the factors which influence the improved results of the-presentl invention have been rigorously proved and I do (not limit my invention to any particular theoretical proof. I believe, however, that at least one factor, and probably an important one in the case of ores containing both molybdenite and other suliides, lies in the fact which I have discovered that ordinary sulfide promoters instead of increasing the recovery of momoters for ordinary metallic suliides such as xanthates, dithiophosphates and the like.

According to the present invention, molybdente is iloated away from the other metallic suldes, preferably by the use of an improved frothling agent which is not an eflcient promoter for the new metallic suliides. This frother is a mixture of higher aliphatic alcohols ranging from 6 to l0 carbon atoms admixed with hydrocarbons of `the -paraiiin and terpene series. Improved grades and recoveries of molybdenite are obtained and when the molybdenite is present with other metallic suldes, the recovery of these other sulildes by subsequent flotation procedure is advantageously affected.

The present invention is applicable to ores which contain molybdenite as the only or substantially the onlyl valuable material and also to ores or concentrates in which molybdenite is admixed with other metallic sulfides, such as for example, copper sulfide. In lthe first case improved molybdenite recoveries are obtained ina single notation procedure and the concentrate can be treated by cleaning or otherwise, to further increase the grade of molybdenite concen- 'Ihis extraordinary result which'is contrary to the effect of ordinary sulfide promoters in ores containinng sulfdes, is one of the important factors in the improved results obtainable when the present invention is applied to ores containing molybdenite in admixture with other suifdes.

It is an advantage of the present invention that it is not Particularly sensitive to pH changes over a considerable range. Excellent results can be obtained in the neutral circuits of many ores. In many other cases circuits of somewhat 'higher pH may be used. However, I have found that lime in large quantitiesis deleterious and much poorer' recoveries are obtained if the ore pulp is conditioned with large quantities of lime, 'I'his action is apparently one 'which is due to Ithe nature of the metal in the base used and not to its basicity as the addition of considerable amounts of bases of the alkali metals such as soda ash does not re.. Suit in any serious lowering of the recovery. With some ores the addition of soda ash to produce a somewhat higher pH is actually helpful. Small amounts ofA lime, not exceeding in any case 1A lb. per ton of ore. do not appear to exert any serious deleterious action. However, if the amount of lime is increased materially beyond such amounts a rapid falling off in the recovery is noted. The relative insensitiveness of the process of the pres ent invention to considerable-changes in pH, pro. vided large amounts of lime are not present, is one advantage of the present invention particularly when applied to ores containing suldes other than molybdenite as a circuit pH can be chosen which will give the best separation between molybdenite and the other metallic sulfldes without adversely aftecting the total molybdenite recovered. The invention is 'therefore applicable toa wide range of molybdenite containing ores and does not require a critical pH control. The deferred to a laboratory size Fagergren flotation machine and diluted to 22% solids with water.

0.09 lb. per ton of ore 'of a frother mixture containing 40% higher aliphatic alcohols, 40% fuel 'oil and 20% pine oil was mixed with the pulp gree to which recoveries are adversely aiected by and the pulp was then subjected to froth 'flota-` the' presence of lime varies widely with dllferent tion. The rougher concentrate was returned to. ores but in every case lime in any considerable the notation machine and cleaned by 'a reflotaquantitiesisundesirable. tion. 0.1 lb. per ton of a copper promoter con- 'I'he invention will be described in greater de- 10 sisting of a 50-50 mixture of the sodium salts of tail in conjunction with the following speciilc exdiethyl dithiophosphoric acid and di-secondary amples and drawingsinwhich: butyl dithiophosphoric acid and 5.50 lbs. of lime Fig. 1 is a flow. sheet representing steps. in a per ton was used in the productionof a second procedure that maybe used in carrying out a difconcentrate from the tailings. The result'l obferential ilotationA of molybedenum and copper tained in-this test are shown in the following sulildes according to the present invention; and table: Table 1 Fig. 2 is a chart illustrating the effect that alkalies have on the recovery of molybdenite 'by Distribution notation' l A Product weight cu Assays The new sheet illustrated in Fig. 1 indicates 20 MS Cu Mos, steps that may be followed in carrying out the l present invention. When the ore to hetreated am Perm, PMM um um is a molybdenite ore substantially free/from other Feed 100.00 1. 81 0. 010 100.00 100.00 Sulfldes @material-i a high rewverytof M082 is tfg 251% $2332 t 22%2 obtainedA .1n a, single step by subjecting the ore 2nd eoneeutrate 1.32 10.20 0.002 03.61 0.13 Pulpw froth-notation employing the impmved trc di? i 3233i 111:29 ""ii frothing mixture composed of higher aliphatic alcchols. fuel 011 and pine 011- When the Ore also The resultsof Example 1 recorded in Table 1 @mains Other mineral @fides Such as @Opper show that 96.33% ef the Mesi was obtained in sulde, a high grade M052 concentrate is mst-'30 the rst otation concentrate, associated with produced using the improved other mixture'a'nd only 21.21% of the.copper sulfide, which conin the absence 0f Promoters for the Coppel' sul'. centrate can very 'easily be improved in grade by ilde. It desirable, copper depressors can beaddthe usual 'methode This represents a marked ed. The tailings are then subjected t"0 froth improvement over prior methods in which pronottion 111 the Presence 0f Coppel' pmmotel's t0 35 moters of suldes are used to obtain a concen- Produce SeCOnd conenmte 11011111 coppel'- The trate relatively high in both molybdenite and mst Step may be carried 0U? in a neutral circuit copper sulfide. It is. also noted that the second 01' in .the case 0f Some 01'35 the PH may be -m' concentrate represents a good copper recovery. creased by the use of certain alkalies or an alkali Em!!! 2 may be added in the second step along with the 40 eepper promu-,en As pointed` eut' heretofore, A series of flotation tests were conducted on large quantities of lime depress molybdenite, a molybdenum ore using various rrothers and therefore lime should not be used in large quanti" .fri-ther mixtures as follows: ties to produce 'the MoSz concentrate, but it can 600 gram Samples of 20 nesh molybdenum Ore l be used to a very good advantage in producing 45 4from the Molybdenum Corporation of America, the subsequent copper concentrate. Figure 2 containing about 4.14% MoSl and a small amount shows graphically the eifect that sodaash and 0f pylite in a gangue COmposed,prilwiially` 0f lime have on molybdenite notation. The curves quartz, was ground at 60% solids in a laboratory illustrate the fact that it is the alkalinity producsize steel rod mill for 'a period of six minutes. ing reagent used that aireets the results rather The ground pulp was transferred to a laboratory than the actual alkalinity or pH changes. size Fagergren flotation machine anddiluted to 22% solids with water. Various frother reagents M 1 were added and conditioned with the pulp for a A 600 gram sample of copper molybdenum ore short time. Air was then admitted-and the refrom the Cananea Consolidated Copper Comsulting froth was removed by skimming. The pany, designated as No. 3-2(R.epub1ica ore) was test products were filtered, dried, weighed and ground at solids in a laboratory size steel assayed. The metallurgical data resulting from rodmill and 0.5 lb. of lime per ton of ore was the tests with the various frothing agents are added to the grind. The ground pulp was transshown in the following table:

Results poor. 'G. N. B.-Geaenl Naval Stena An examination of Table 2 shows that the 'frothing vreagents composed of a mixture of higher aliphatic alcohols having 6 to 10 carbon atoms, a paraflin hydrocarbon such as fuel oil, and a hydrocarbon of the terpene series such as pine oil, produced higher recoveries of molybdenite than were produced when such alcohols or hydrocarbons were used separately. Test #4 using a higher aliphatic alcohol resulted in a recovery of only 82.83% MoSz and test #5 using pine oil produced a concentrate containing konly '79.2% MoSz, and yet mixtures of the two with fuel oil as shown in testsv#6, 7, and8 increased the MoSz recovery in the concentrate to 87.90%. This not only represents a very marked improvement in recovery but also an unexpected improvement.'

WhatIclaim is: 1. A process for the recovery froth flotation which comprises subjecting an aqueous pulp containing molybdenite a-froth notation operation in the presence of an effective amount of a collector for the molybdenite, said of molybdenite by I collector comprising a. composition containing at least one higher aliphatic alcohol having six to ten carbon atoms, a hydrocarbon of the paraffin series and a hydrocarbon of the terpene series, the alcohol content of the composition being substantially 40 2. A process for the recovery of molybdenite by froth flotation which comprises subjecting an aqueous pulp containing molybdenite lto a froth Q flotation operation in the presence of an effective amount of a collector for the molybdenite, said collector comprising a composition' containing approximately 40% of a mixture of higher aliphatic alcohols having from six to ten carbon atoms, about oil.

3. A process for the recovery of molybdenite by froth flotation -which comprises subjecting an aqueous pulp containing molybdenite-to a froth flotation operation in the presence of angifective amount of a collector for the molybdenite. said collector comprising a composition containing 40% fuel oil and about 20% pine,

approximately 40% of a mixture of higher aliphatic alcohols having from six to ten carbon atoms, about 40% fuel oil and about 20% pine oil, and in the absence of an effective amount of a collector for other sulfid ores.

4. A process for separating molybdenite from other metallic sulfides which comprises the steps of subjecting an ore containing bothto froth flotation in the presence of an effective amount of a collectorV for the molybdenite which comprises a vcomposition containing at least one higher aliphatic alcohol having six to ten carbon atoms, a hydrocarbon of the paramn series and a hydrocarbon of the terpene series; and in the absence of an effective promoter for the other metallic sulndes, whereby a concentrate is obtained representing a high recovery of molybdenite in the ore and a Vrelatively low recovery of the other metallic sulildes, subjecting the tailings' to froth flotation in the presence of an eifective amount of a promoter for said other sulides producing a second concentrate representing a relatively high recovery of at least-.one of the other metallic sulildes, the alcohol content of the composition being substantially 40%.

5. A process for separating molybdenite from other metallic sulildes which comprises the steps of subjecting an ore containing both to froth flotation in the presence of an effective amount of a collector for the modybdenite which comprises a composition containing approximately 4,0% of a mixture of higher aliphatic alcohols having from six to ten carbon atoms, about 40% fuel oil l coRBrN MARSH. 

